Do some work on redbean

- Rewrite Slurp() API to be like string.sub()
- Introduce a new Barf() API for creating files
- Update Redbean `-S` sandbox flag to do unveiling

test/tool/net/slurp_test.lua

@@ -0,0 +1,50 @@
+-- Copyright 2022 Justine Alexandra Roberts Tunney
+--
+-- Permission to use, copy, modify, and/or distribute this software for
+-- any purpose with or without fee is hereby granted, provided that the
+-- above copyright notice and this permission notice appear in all copies.
+--
+-- THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL
+-- WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED
+-- WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE
+-- AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
+-- DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
+-- PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
+-- TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+-- PERFORMANCE OF THIS SOFTWARE.
+
+tmpdir = "o/tmp/lunix_test.%d" % {unix.getpid()}
+
+local function Path(name)
+   return tmpdir .. '/' .. name
+end
+
+local function SlurpTest()
+
+   data = 'abc123' * 5000
+   assert(Barf(Path('foo'), data))
+   assert(assert(Slurp(Path('foo'))) == data)
+   assert(assert(Slurp(Path('foo'), 2, 3)) == 'bc')
+   assert(assert(Slurp(Path('foo'), 2)) == data:sub(2))
+   assert(assert(Slurp(Path('foo'), 2, 1)) == data:sub(2, 1))
+   assert(assert(Slurp(Path('foo'), 2, 2)) == data:sub(2, 2))
+   assert(assert(Slurp(Path('foo'), 1, 2)) == data:sub(1, 2))
+   assert(assert(Slurp(Path('foo'), -3, -1)) == data:sub(-3, -1))
+
+   assert(Barf(Path('foo'), 'XX', 0, 0, 3))
+   assert(assert(Slurp(Path('foo'), 1, 6)) == 'abXX23')
+
+end
+
+local function main()
+   assert(unix.makedirs(tmpdir))
+   ok, err = pcall(SlurpTest)
+   if ok then
+      assert(unix.rmrf(tmpdir))
+   else
+      print(err)
+      error('SlurpTest failed (%s)' % {tmpdir})
+   end
+end
+
+main()